Digital computer systems have been developed for storing and processing information in a plurality of structured forms. Problems arise, however, when it is desired to process information which can have a variety of structures, such as textual information, to determine its semantic content. Several systems have been developed to enable computers to attempt to process textual information in relatively narrow and limited fields. For example, in some systems, the textual information is scanned to identify key words or their synonyms and their relationships, from which the system attempts to determine the semantic content of the textual information, in response to which the computer may perform some predetermined operation. In other systems, the textual information is parsed using a syntactic grammar, and a parse tree developed. Using the parse tree, the system also attempts to determine the semantic content of the textual information, in response to which the computer may perform some predetermined operation. Both types of systems are generally useful only in connection with textual information of relatively well-defined structure and content, and are difficult and expensive to maintain.